The present invention relates to a connection system for the aligned connection of two tool parts.
In particular in the case of rotary tools for cutting, there are numerous interfaces between the different tool parts. The alignment in which the two tool parts are attached to each other is often important. If, for example, one of the two tool parts bears a cutting bit, then an exact alignment of the two tool parts to each other is generally necessary in order to achieve a satisfactory cutting result.
Thus for example a connection system is known from U.S. Pat. No. 5,857,811 for the attachment of a cutting edge holder (cutting bit holder) to a tool holder of a boring head. Here, the cutting edge holder has a groove which is fitted onto a correspondingly shaped driving key of the tool holder. Attachment then takes place with the help of a screwed connection. The groove is essentially arranged in the circumferential direction of the tool holder, with the result that by fitting the bit holder onto the tool holder, an alignment or positioning of the cutting bit holder in the axial direction takes place. In the radial direction, on the other hand, the alignment takes place exclusively through the tensioning screw, which can, however, lead to slight misalignments.
It is further provided with this attachment system that the driving key is oversized, i.e., it is larger in cross-section than the groove prior to insertion of the driving key into the groove, with the result that when the cutting bit holder is placed on the driving key and the cutting bit holder is tightened with the help of a tensioning screw, an elastic deformation of the sides of the groove and/or the driving key occurs. That ensures a play-free connection and also makes it possible to transfer cutting forces between the groove and the driving key. However, it proves difficult to subsequently detach the cutting bit holder from the tool holder as, because of the elastic deformation of the groove and/or the key, the bit holder is stuck on the driving key even after the tensioning spring has been loosened. Therefore it is frequently necessary to also provide a push-off mechanism, for example in the form of a screw whose foot pushes the cutting bit holder away from the tool holder when the screw is tightened.
A connection system is already described in U.S. Pat. No. 4,834,597 in which a first tool part has a truncated projection which faces a second tool part, while the second tool part has a seat which is defined by a tapering recess in order to receive the projection of the first part. Furthermore, with this attachment system, devices are provided for clamping the first tool part to the second tool part. Both the projection and the recess have a non-circular cross-section. However, here too the projection is oversized relative to the recess, with the result that when the projection is inserted into the recess there is an elastic expansion of the recess and/or a compression of the projection. In principle an exact alignment of the two tool parts relative to each other is possible with this connection system. Here, too, however it is also not always easy to detach the two tool parts from each other, as, after the tensioning screw has been loosened, the one tool part may be stuck on the second tool part. A suitable push-off device must therefore be present with the help of which the one tool part can be pushed off from the other tool part.
The attachment systems described in the state of the art either do not permit an easy alignment of the two tool parts to each other or are suitable only for relatively large tools in which the additional push-off device can be integrated.
Starting from this state of the art, it is therefore an object of the invention to provide a connection system for the aligned connection of two tool parts which is easy and economical to produce, which makes possible an exact alignment in both the axial and the radial direction and with which the provision of an additional push-off device can be dispensed with.